CN100444791C - Magnetic resonance imaging device, and data processing method of magnetic resonance imaging device - Google Patents
Magnetic resonance imaging device, and data processing method of magnetic resonance imaging device Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
- G01R33/341—Constructional details, e.g. resonators, specially adapted to MR comprising surface coils
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Abstract
A magnetic resonance imaging apparatus 20 includes a scan executing unit that executes scan to generate sensitivity map data of an RF coil 24, a region reduction unit 44b that applies region reduction to a signal region near a no-signal region of image data obtained by the scan, a sensitivity map data generating unit 44 that generates sensitivity map data using image data after the region reduction, and a smoothing processing unit 44i that applies three-dimensional smoothing filter to the sensitivity map data.
Description
Technical field
The present invention relates to utilize NMR signal detected volume image to be implemented Magnatic Resonance Imaging (MRI) apparatus and the data processing method of Magnatic Resonance Imaging (MRI) apparatus, the pictorial data brightness of the generation that particularly can distribute and the Magnatic Resonance Imaging (MRI) apparatus of the inhomogeneities enforcement correction of signal value and the data processing method of Magnatic Resonance Imaging (MRI) apparatus that videotapes to the sensitivity of signal receiving coil.
Background technology
Formerly in the technology as the on-the-spot checkout gear that uses of medical treatment, comprise as shown in figure 24 magnetic resonance imaging (MRI:Magnetic Resonance Imaging) device 1 (such as can referring to No. 3135592 communique of Japan Patent).
Magnatic Resonance Imaging (MRI) apparatus 1 is following such device: can be by being positioned at the location that videotapes that forms detected body P that tubular magnetostatic field that magnetostatic field uses locates with the inside of Magnet 2, each gradient magnetic field coil 3x by gradient magnetic field coil assembly 3,3y, 3z forms along X-axis, Y-axis, the leaning magnetic field of Z-direction, and implement to transmit by high frequency (RF) signal of RF (Radio Frequency) 4 couples of Larmors of coil (Larmor) frequency, make the nuclear spin that is positioned at the inner place of detected body P produce magnetic resonance, and nuclear magnetic resonance, NMR (the NMR:Nuclear Magnetic Resonance) signal that utilizes excitation to be produced implement to reconstruct processing to the image of detected body P.
In other words be exactly to use magnetostatic field to use the inside of Magnet 2 to form magnetostatic field at magnetostatic field in advance with power supply 5.According to the command signal that receives by input equipment 6, to be sent to sequence signal controller 8 places as the sequence signal of signal controlling information by sequence signal controller Control Component 7a, and then by sequence signal controller 8 according to sequence signal, implement control to high-frequency signal being sent to the leaning magnetic field that is connected with each gradient magnetic field coil 3x, 3y, 3z with the sender unit 10 at power supply 9 and RF coil 4 places.Adopt this form of the composition, can videotape location formation leaning magnetic field, and can send out high-frequency signal to detected body P.
By X-axis leaning magnetic field, Y-axis leaning magnetic field, the Z axle leaning magnetic field that at this moment gradient magnetic field coil 3x, 3y, 3z produce, mainly be respectively as phase code (PE:phase encoding) with leaning magnetic field, read (RO:readout) and use with leaning magnetic field with leaning magnetic field, aspect coding (SE:slice encoding).Therefore,, be transformed to phase place, the frequency of nuclear spin, the position of aspect respectively as X coordinate, Y coordinate, the Z coordinate of atomic nucleus positional information, Yi Bian and change the phase code amount, Yi Bian repeat the sequence operation.
Then, be accompanied by the NMR signal that excitation is produced is implemented in the nuclear spin that is positioned at the inner place of detected body P, utilize RF coil 4 received signals, be sent to signal receiver 11 places simultaneously and be transformed to digitized initial data (raw data).This initial data can read to sequence signal controller Control Component 7a place by sequence signal controller 8, and then by sequence signal controller Control Component 7a initial data is configured in and is formed on initial data and locates with the K space (fourier space) at data base 7b place.Image reconstructs assembly 7c can obtain the pictorial data that reconstructs of detected body P by the initial data that is configured in place, K space is implemented Fourier transform, and it is stored in pictorial data data base 7d place.And, can also pictorial data be sent to appropriate display device 7f place by display process assembly 7e, so that it is implemented to show.
This Magnatic Resonance Imaging (MRI) apparatus 1 is in order to improve camera speed, adopting the form of the composition that RF coil 4 is made of the phased matrix coils (PAC:phased-array coil) of the main coil that sends integral body (WB:whole-body) coil that signal uses and use as received signal (such as can be referring to Roemer PB, et al, The MNR Phased Array, MRM 16,192-225 (1990)).Phased matrix coils has a plurality of surface coils, so can videotape the needed time to collect the mode of more initial datas in the short time, to shorten by using each surface coils to receive the NMR signal simultaneously.
When adopting this Magnatic Resonance Imaging (MRI) apparatus 1 to implement image diagnosis, do not wish in the final pictorial data that obtains, luminance fluctuation (unevenness) (signal intensity fluctuating) to occur.Yet, when RF coil 4 is when being made of the phased matrix coils with a plurality of surface coils, owing to constitute the sensitivity inhomogeneities of each surface coils of RF coil 4 usefulness, can make the signal intensity of NMR signal and simply initial data be implemented Fourier transform etc. to reconstruct the signal intensity of handling the pictorial data that obtains and produce inhomogeneities, so can make pictorial data produce luminance fluctuation.
Therefore, formerly be in the technology before the main scanning that implement to generate detected body P image usefulness, carry out the sensitivity prescan earlier.So, utilize WB coil and phased matrix coils to obtain pictorial data by the sensitivity prescan, and by process step shown in Figure 25, according to the signal intensity S as each pictorial data
PAC, S
WBThe signal intensity ratio (S of division arithmetic value
PAC/ S
WB), the sensitivity as the phased matrix coils of three-dimensional sensitivity map diagram data distributed implement to infer, and then the three-dimensional sensitivity map diagram data that passes through to be obtained is implemented to revise to the brightness of pictorial data.
At first, by sensitivity prescan operating component 7g sensitivity is inferred with sequence signal and to be sent to sequence signal controller Control Component 7a place, implement the operation of sensitivity prescan.The PAC that will reconstruct image by the WB that the WB coil obtains and obtain by phased matrix coils reconstructs image, is stored in WB respectively and reconstructs image and reconstruct image data base 7i place with data base 7h and PAC.
Subsequently, distribute by sensitivity and to infer that assembly 7j reconstructs image according to WB and PAC reconstructs image, find the solution the presumed value of the sensitivity distribution of phased matrix coils.
In other words be exactly in step S1, WB to be reconstructed image and PAC reconstructs image enforcement threshold process by the 7k of threshold process portion.WB is reconstructed each signal intensity that image and PAC reconstruct image smaller or equal to the zone of threshold value (comprising this threshold value) enforcement shielding processing (mask), and generate WB absolute value pictorial data and PAC absolute value pictorial data.
Subsequently in step S2, suppress handling (region reduction) 7l of portion by the zone reconstructs zone after the threshold process that image and WB reconstruct image and implements the zone and suppress processing implementing PAC, to be positioned at the smaller part of signal intensity of the shielding area vicinity after dwindling, remove the data of when three-dimensional sensitivity map diagram data is made, using.
Subsequently in step S3, by division arithmetic handling part 7m by the PAC absolute value image (PAC reconstructs the signal absolute value of image) in each aspect after threshold process and zone suppress are handled, divided by the mode of WB absolute value image (WB reconstructs the signal absolute value of image), PAC absolute value image and the signal intensity ratio between WB absolute value image as three-dimensional sensitivity map diagram data are implemented to find the solution.
In step S4,, handle subsequently by each aspect execution standardization by the three-dimensional sensitivity map diagram data of the 7n of standardization portion to solving as the signal intensity ratio between PAC absolute value image and WB absolute value image.
Subsequently in step S5, be positioned at the no signal zone at the inner place of detected body P in the three-dimensional sensitivity map diagram data after by detected interior body region interpolation handling part 7o execution standardization being handled, implement the line style interpolation and handle.
Subsequently in step S6, for being distributed, the sensitivity that is arranged in no signal zone, detected external body place implements to infer, implement the zone by detected external regional interpolation handling part 7p and increase (regiongrowing) processing, the sensitivity in the no signal zone, detected external body place is distributed implement interpolation thus.
Subsequently in step S7, for make distribute along the sensitivity of cutting bedding angle the same, and by bedding angle weighting handling part 7q to three-dimensional sensitivity map diagram data along cutting aspect weighted direction, thus it is implemented correcting process.
Subsequently in step S8, implement such as various processing such as data fitting processing and level and smooth (smoothing) processing by the 7r of smoothing processing portion, producing sensitivity map figure, and be stored in sensitivity map figure with data base 7s place as the volume data in the whole 3D region.
Subsequently, image can be obtained to be sent to sequence signal controller Control Component 7a place with sequence signal by main scanning operating component 7t the operation main scanning.Reconstruct assembly 7c enforcement image by image and reconstruct processing, and the pictorial data that is obtained is stored in pictorial data data base 7d place.Pictorial data correction assembly 7u utilizes and is stored in the sensitivity map figure of sensitivity map figure with data base 7s place, implement to revise with the brightness of the pictorial data at data base 7d place to being stored in pictorial data, and the pictorial data that will implement after the brightness correction by display process assembly 7e is sent to display device 7f place, shows implementing.
In general, include the no signal zone in the pictorial data by sensitivity prescan and main scanning acquisition.At the position that has as the detected body place that videotapes the zone such as lung etc., so have the no signal zone that can not produce the NMR signal.And, being positioned at detected intravital no signal zone and the signal area that has of boundary vicinity position between the signal area is arranged, the smaller phenomenon of signal intensity can appear usually.And this can exert an influence to the sensitivity distribution presumed value of phased matrix coils.
Yet, belonging to the Magnatic Resonance Imaging (MRI) apparatus 1 of technology formerly, no signal zone interpolating method when making the sensitivity map figure of phased matrix coils and is positioned at detected inside and outside and irrespectively only the zone is implemented in the no signal zone and increase and handle.
And, use phased matrix coils sensitivity prescan of implementing and the sensitivity prescan that uses the WB coil to implement to implement respectively, so the shape of the detected body P in the pictorial data of using phased matrix coils to obtain, and tend to occur deviation between the shape of the detected body P in the pictorial data of use WB coil acquisition.
And the sensitivity that is not each surface coils at phased matrix coils place distributes, also can owing to configuration feature produce with install coordinate system in the relevant signal intensity inhomogeneities of Z-direction.
Yet, belong to the Magnatic Resonance Imaging (MRI) apparatus 1 of technology formerly, the signal intensity inhomogeneities that the pictorial data position deviation when not considering enforcement sensitivity prescan and the configuration feature of surface coils produce, only be WB to be reconstructed each signal intensity that pictorial data and PAC reconstruct pictorial data implement threshold process, and, the sensitivity distribution of phased matrix coils is implemented to infer and generate sensitivity map figure according to PAC absolute value pictorial data that obtains respectively thus and the signal intensity ratio between WB absolute value pictorial data.
Owing to adopt this form of the composition, belong to the Magnatic Resonance Imaging (MRI) apparatus 1 of technology formerly, be difficult to make the sensitivity distribution of the phased matrix coils of inferring out to have good accuracy, have the problem of the correction of good accuracy so have the brightness enforcement that reconstructs image that is difficult to implementing the main scanning acquisition by the sensitivity prescan.
And, formerly in the technology as the on-the-spot checkout gear that uses of medical treatment, also comprise as shown in figure 26 Magnatic Resonance Imaging (MRI) apparatus 1 (such as can referring to No. 3135592 communique of Japan Patent).
As mentioned above, when RF coil 4 is when being made of phased matrix coils and WB coil, the NMR signal relevant with the sensitivity inhomogeneities of phased matrix coils and WB coil, and by the signal intensity that reconstructs the pictorial data that processing mode obtains also inhomogeneities can appear.In general, the sensitivity inhomogeneities of WB coil is little of can uncared-for degree, yet the sensitivity inhomogeneities as the surface coils in the phased matrix coils of the coil that is provided with for other technical purpose is then bigger, can exert an influence to pictorial data.
Therefore, the inhomogeneities in the viewdata signal intensity that is necessary the sensitivity inhomogeneities owing to phased matrix coils is produced is implemented to revise.
Magnatic Resonance Imaging (MRI) apparatus 1 as shown in figure 26, can be according to shown in the indicative flowchart of Figure 27, in step S1, pass through sensitivity prescan operating component 7g, sensitivity inferred with sequence signal is sent to sequence signal controller Control Component 7a place, with phased matrix coils and WB coil as the signal receiving coil and implement the operation of sensitivity prescan.Will be by the WB circuit diagram image data of WB coil acquisition and the main coil pictorial data that obtains by phased matrix coils, infer the pictorial data of usefulness as the sensitivity distribution of phased matrix coils and implement to obtain, and be stored in WB coil image data base 7h and main coil image data base 7v place respectively.Adopt this form of the composition, can be by twice mode to implementing to videotape as the volume data of three-dimensional image data.
In step S2, infer assembly 7j by the sensitivity distribution sensitivity distribution presumed value of phased matrix coils is implemented to find the solution subsequently.In other words be exactly, to utilize the signal intensity S of the WB circuit diagram image data shown in Figure 28 (b) by using division arithmetic handling part 7w
WB, to the signal intensity S of the main coil pictorial data shown in Figure 28 (a)
PACImplement the mode of division operation, obtain as main coil pictorial data sensitivity distribution presumed value, shown in Figure 28 (c) of phased matrix coils and the signal intensity ratio (S between WB circuit diagram image data
PAC/ S
WB).
At this moment, for not to the signal intensity S of main coil pictorial data and WB circuit diagram image data
PAC, S
WBLess than threshold value (not comprising this threshold value) such as less than the zone of peaked 10% (not comprising 10%), implement division arithmetic and handle, can use the 7x of threshold process portion to implement each signal intensity S as required as the division arithmetic pre-treatment
PAC, S
WBThreshold process, to being positioned at each signal intensity S less than the location of threshold value (not comprising this threshold value)
PAC, S
WBImplement shielding.
By implementing with of the division arithmetic processing of this threshold process as pre-treatment, can eliminate such as the principal element outside sensitivity skewness image contrast etc., phased matrix coils the influence that the signal intensity of pictorial data produces, implement infer thereby can distribute to sensitivity according to mode with good accuracy.
Subsequently, to because the existence of the lobe of the lung etc. and the no signal zone of the data missing part that when implementing threshold process, produces, using interpolation handling part 7y to implement interpolation handles or extrapolation process, distribution is implemented to infer to sensitivity, and then pass through the 7z of smoothing processing portion to whole 2 dimensional region implementation data process of fitting treatment and smoothing processing, obtain the sensitivity distribution presumed value curve shown in Figure 28 (d).
Then, each section of whole 3D region is implemented same pictorial data handle, solve sensitivity distribution presumed value as volume data.
Subsequently in step S3, will be as the sensitivity distribution presumed value of the phased matrix coils of three-dimensional sensitivity map diagram data, be stored in sensitivity map figure with data base 7s place.
In step S4, image is obtained to be sent to sequence signal controller Control Component 7a place with sequence signal by main scanning operating component 7t subsequently, under with the condition of phased matrix coils, move main scanning as the signal receiving coil.Initial data implement collected and reconstruct the image that assembly 7c implements by image reconstruct processing, obtain pictorial data.
Subsequently in step S5, according to videotaping the corresponding mode of each condition that condition, data collection condition, image reconstruct condition etc. such as videotaping profile direction, spatial resolution etc. when implementing main scanning, by pictorial data correction assembly 7u from sensitivity map figure with obtaining out corresponding three-dimensional sensitivity map diagram data the data base 7s.
In step S6, pictorial data correction assembly 7u utilizes the three-dimensional sensitivity map diagram data that is obtained out subsequently, and pictorial data is implemented correcting process.Adopt this mode, can improve the signal intensity inhomogeneities of pictorial data.
On the other hand, also adopt following method: implement post processing by the pictorial data self that the NMR signal that uses phased matrix coils to receive is obtained, come the sensitivity as the phased matrix coils of sensitivity map diagram data distributed and implement to infer, and then utilize the sensitivity map diagram data of the phased matrix coils obtained, the signal intensity of pictorial data is risen and fallen implement to revise.If for instance, can adopt by the pictorial data of using phased matrix coils to obtain being implemented the mode of smoothing processing, produce pictorial data with extremely low frequency composition, and with its method that distributes and use as sensitivity.
And, following scheme is also proposed: as a reference with the signal intensity of implementing the high-frequency signal that signal sends from the WB coil, to the signal intensity of the pictorial data that obtains by the NMR signal that receives by the phased matrix coils technology implementing to revise (such as can referring to Japanese kokai publication sho 63-132645 communique) that rises and falls, and the sensitivity that utilizes the phased matrix coils that stores in advance distributes and implement to infer the positional information of the phased matrix coils that is obtained from pictorial data, to the signal intensity of the pictorial data technology implementing to revise (such as can referring to Japanese kokai publication hei 7-59750 communique) that rises and falls.
Yet, if adopt in the technology formerly when implementing the sensitivity prescan respectively signal strength values Sig by the pictorial data of phased matrix coils and the acquisition of WB coil
PAC, Sig
WBDivision arithmetic value (Sig
PAC/ Sig
WB), the sensitivity distribution of phased matrix coils to be implemented to infer, when thus the signal intensity of pictorial data being implemented the method for correction, long problem of needed time of sensitivity prescan can appear implementing.Therefore, for the occasion of the abdominal part of for example detected body P being implemented videotape, with suspend breathing time the running time of sensitivity prescan accordingly also can be long.
And, collect with using the WB coil and implement between pictorial data collects using phased matrix coils to implement pictorial data, might move etc. former thereby cause the position deviation (error logging) of detected body P owing to detected body P.And, in order to obtain pictorial data, also need to make the form of the composition that forms complete decoupling (decoupling) between phased matrix coils and WB coil by phased matrix coils and WB coil.
On the other hand, distribute at the sensitivity that uses the phased matrix coils that pictorial data self the enforcement post processing that is provided by phased matrix coils is inferred out, signal intensity fluctuating to pictorial data is implemented in the method for correction, since to the sensitivity of phased matrix coils distribute to infer ratio of precision lower, so be difficult to the signal intensity fluctuating of pictorial data is implemented fully to revise, thereby be difficult to make the revised pictorial data of final acquisition to have sufficient uniformity.
And, also have the problem that is difficult to various visual kinds are implemented the good correcting process of precision usually.If for instance, emphasizing the mode emphasized with T2 by pictorial data being carried out T1, making pictorial data is the occasion with pictorial data of desirable contrast, promptly allow to sensitivity distribution enforcement be inferred by smoothing processing, because the pictorial data that the expression sensitivity distributes has contrast, use so also be difficult to use the pictorial data of implementing after the smoothing processing to distribute as sensitivity.
And, also have when implementing to videotape by multiple aspect mode always, be difficult to whole aspects are implemented the problem of pictorial data correction.
Summary of the invention
The present invention is exactly the invention that solves the problems of the technologies described above usefulness, purpose of the present invention just provide a kind of can be according to by implementing the pictorial data that the sensitivity prescan obtains, more high-precision inferring implemented in sensitivity distribution to the RF coil, thereby can distribute according to the sensitivity of the RF coil that is obtained, the good Magnatic Resonance Imaging (MRI) apparatus of revising is implemented in the brightness of the pictorial data that obtains implementing main scanning, and the data processing method of Magnatic Resonance Imaging (MRI) apparatus.
Another object of the present invention just provide a kind of can be in the shorter time, according to videotaping the mode of conditional independence with visual kind etc., the signal intensity of the pictorial data that the inhomogeneities that the sensitivity of signal receiving coil is distributed causes rises and falls and implements the Magnatic Resonance Imaging (MRI) apparatus of the good correction of precision, and the data processing method of Magnatic Resonance Imaging (MRI) apparatus.
In order to realize above-mentioned purpose, a kind of Magnatic Resonance Imaging (MRI) apparatus provided by the invention has: assembly is implemented in the scanning of carrying out the scanning operation that the sensitivity map diagram data be used to generate the RF coil uses; The position has a signal area near the no signal zone of the pictorial data that aforementioned scanning operation is obtained, and implements the zone that the zone suppresses to handle and suppresses processing components; Use the earlier figures image data of implementing after the zone suppresses to handle, generate the sensitivity map diagram data formation component of sensitivity map diagram data; And the smoothing processing assembly of aforementioned sensitivity map diagram data being implemented three-dimensional The disposal of gentle filter.
And in order to realize above-mentioned purpose, another kind of Magnatic Resonance Imaging (MRI) apparatus provided by the invention has: assembly is implemented in the scanning of carrying out the scanning operation that the sensitivity map diagram data be used to generate the RF coil uses; Use the pictorial data that obtains by aforementioned scanning operation, generate the sensitivity map diagram data formation component of sensitivity map diagram data; The linear interpolation processing components that linear interpolation is handled is implemented in the inner no signal zone of locating of the detected body of aforementioned sensitivity map diagram data; And the smoothing processing assembly of aforementioned sensitivity map diagram data being implemented three-dimensional The disposal of gentle filter.
And, in order to realize above-mentioned purpose, another Magnatic Resonance Imaging (MRI) apparatus provided by the invention has: the signal receiving coil in the time of will implementing above-mentioned image and videotape is as the signal receiving coil, carries out the scanning of the scanning operation of the sensitivity correction data that are used to generate the signal receiving coil that aforementioned image videotapes and implements assembly; And only the data that obtain of the signal receiving coil when videotaping by aforementioned image in the aforementioned scanning operation generate the sensitivity correction data formation component of aforementioned sensitivity correction with data as initial data.
And, in order to realize above-mentioned purpose, the data processing method of a kind of Magnatic Resonance Imaging (MRI) apparatus provided by the invention has: the pictorial data that the scanning of the sensitivity map diagram data of implementing to be used to generate the RF coil is obtained be positioned near the no signal zone the signal area that has, implement the zone and suppress the step handled; Use the earlier figures image data of implementing after the zone suppresses to handle, generate the step of sensitivity map diagram data; And the step of aforementioned sensitivity map diagram data being implemented three-dimensional The disposal of gentle filter.
And, in order to realize above-mentioned purpose, the data processing method of another kind of Magnatic Resonance Imaging (MRI) apparatus provided by the invention has: use to implement to be used to generate the scanning of sensitivity map diagram data of RF coil and the pictorial data that obtains, generate the step of sensitivity map diagram data; The step that linear interpolation is handled is implemented in the no signal zone that is positioned at detected body inside to aforementioned sensitivity map diagram data; And the step of aforementioned sensitivity map diagram data being implemented three-dimensional The disposal of gentle filter.
And, in order to realize above-mentioned purpose, the data processing method of another Magnatic Resonance Imaging (MRI) apparatus provided by the invention has: will implement the signal receiving coil of image when videotaping as the signal receiving coil, and carry out the sensitivity correction that is used to generate the signal receiving coil that aforementioned image the videotapes step with the scanning of data; And the data that only the signal receiving coil that videotapes by aforementioned image in the aforementioned scanning operation obtained generate the step of aforementioned sensitivity correction with data as initial data.
Data processing method according to Magnatic Resonance Imaging (MRI) apparatus of the present invention and Magnatic Resonance Imaging (MRI) apparatus, the pictorial data that can obtain according to implementing the sensitivity prescan, with high accuracy more the sensitivity of RF coil is distributed and to implement to infer, and then can distribute according to the sensitivity of the RF coil that is obtained, to implementing more good correcting process by the brightness of implementing the pictorial data that main scanning obtains.
And, can also be in the shorter time, videotape conditional independence ground with visual kind etc., the signal intensity of the pictorial data that the inhomogeneities that the sensitivity of signal receiving coil is distributed causes rises and falls and implements the good correction of precision.
Description of drawings
Fig. 1 is the functional-block diagram of a kind of form of implementation of expression Magnatic Resonance Imaging (MRI) apparatus of the present invention.
Fig. 2 is the detailed pie graph of RF coil shown in the presentation graphs 1 and signal receiver.
Fig. 3 is the profile schema diagram of a profile instance of WB coil shown in the presentation graphs 2 and phased matrix coils.
The flow chart of the step when Fig. 4 uses the Magnatic Resonance Imaging (MRI) apparatus shown in Fig. 1 that detected body enforcement cross-sectional image is videotaped for expression.
The flow chart of the detailed step when Fig. 5 uses the Magnatic Resonance Imaging (MRI) apparatus shown in Fig. 1 to generate sensitivity map diagram data for expression.
Fig. 6 implements the figure that the zone suppresses an example of processing for representing by the Magnatic Resonance Imaging (MRI) apparatus shown in Fig. 1.
Fig. 7 implements a figure that example use that linear interpolation handle by the Magnatic Resonance Imaging (MRI) apparatus shown in Fig. 1 to the no signal zone that is arranged in detected body inside of three-dimensional sensitivity map diagram data for expression.
Fig. 8 implements key diagram that zone increase the occasion handled by 26 point methods to the no signal zone that is positioned at detected external body of three-dimensional sensitivity map diagram data for explanation.
Fig. 9 implements key diagram that zone increase the occasion handled by 6 point methods to the no signal zone that is positioned at detected external body of three-dimensional sensitivity map diagram data for explanation.
Figure 10 implements figure that zone increase an example handling by the Magnatic Resonance Imaging (MRI) apparatus shown in Fig. 1 to the no signal zone that is positioned at detected external body of three-dimensional sensitivity map diagram data for expression.
Figure 11 uses the curve chart of the Magnatic Resonance Imaging (MRI) apparatus shown in Fig. 1 to the correction factor of three-dimensional sensitivity map diagram data when the cutting bedding angle is implemented weighting and handled for expression.
Figure 12 uses the figure of the cross-sectional image of the detected body after the brightness correction that the Magnatic Resonance Imaging (MRI) apparatus shown in Fig. 1 obtains for expression.
The figure of the cross-sectional image of the detected body after the brightness correction that Figure 13 obtains for the Magnatic Resonance Imaging (MRI) apparatus in the expression priority of use technology.
Figure 14 is the functional-block diagram of second form of implementation of expression Magnatic Resonance Imaging (MRI) apparatus of the present invention.
Figure 15 is the detailed pie graph of an example of RF coil shown in expression Figure 14 and signal receiver.
The flow chart of the step when Figure 16 uses the Magnatic Resonance Imaging (MRI) apparatus shown in Figure 14 that detected body enforcement cross-sectional image is videotaped for expression.
Figure 17 is illustrated in the flow chart shown in Figure 16, the sensitivity distribution enforcement of phased matrix coils is pushed away the flow chart of an example of periodic detailed step.
Figure 18 is illustrated in the figure that low contrast videotapes the signal intensity profile of the main coil pictorial data that obtains under the condition.
Figure 19 is illustrated in the figure that conventional contrast videotapes the signal intensity profile of the main coil pictorial data that obtains under the condition.
Figure 20 implements the figure of the data that generated when three-dimensional sensitivity map diagram data generates for the Magnatic Resonance Imaging (MRI) apparatus in the expression priority of use technology.
Figure 21 is the key diagram that existing problem when using the Magnatic Resonance Imaging (MRI) apparatus shown in Figure 14 to implement three-dimensional sensitivity map diagram data generates is described.
Figure 22 for expression by can avoiding the step of problem as shown in figure 21, the figure of the data that generated when using Magnatic Resonance Imaging (MRI) apparatus as three-dimensional sensitivity map diagram data.
Figure 23 is the functional-block diagram of the 3rd form of implementation of expression Magnatic Resonance Imaging (MRI) apparatus of the present invention.
Figure 24 is a functional-block diagram of representing a kind of Magnatic Resonance Imaging (MRI) apparatus in the technology formerly.
Figure 25 generates the flow chart of the step of sensitivity map figure by the Magnatic Resonance Imaging (MRI) apparatus of the technology formerly shown in Figure 24 for expression.
Figure 26 is a functional-block diagram of representing a kind of Magnatic Resonance Imaging (MRI) apparatus in the technology formerly.
Figure 27 implements the flow chart of the step of correction to the viewdata signal intensity fluctuation by the Magnatic Resonance Imaging (MRI) apparatus of the technology formerly shown in Figure 26 for expression.
Figure 28 infers the key diagram of the step of sensitivity distribution by the Magnatic Resonance Imaging (MRI) apparatus of the technology formerly shown in Figure 26 for explanation.
The specific embodiment
Below with reference to accompanying drawing, the form of implementation of the data processing method of Magnatic Resonance Imaging (MRI) apparatus of the present invention and Magnatic Resonance Imaging (MRI) apparatus is described.
Fig. 1 is the functional-block diagram of first form of implementation of expression Magnatic Resonance Imaging (MRI) apparatus of the present invention.
Magnatic Resonance Imaging (MRI) apparatus 20 constitutes: will form tubular magnetostatic field that magnetostatic field uses with Magnet 21, be arranged on equal field coil (shim coil) 22 and gradient magnetic field coil assembly 23 and the RF coils 24 of this magnetostatic field with Magnet 21 inner places, be installed in the not shown frame.
And, in Magnatic Resonance Imaging (MRI) apparatus 20, also be provided with control system 25.Control system 25 has magnetostatic field power supply 26, leaning magnetic field power supply 27, equal field coil power supply 28, sender unit 29, signal receiver 30, sequence signal controller 31 and computer 32.Leaning magnetic field in the control system 25 is made of with power supply 27z with power supply 27y and Z axle leaning magnetic field with power supply 27x, Y-axis leaning magnetic field the X-axis leaning magnetic field with power supply 27.And computer 32 has not shown arithmetic unit and storage device, and is provided with input equipment 33 and display device 34.
Magnetostatic field is connected with power supply 26 with magnetostatic field with Magnet 21, and has and can videotape the regional function that forms magnetostatic field by the electric current of being supplied with power supply 26 by magnetostatic field.And, at the inboard place of magnetostatic field, the equal field coil 22 of cartridge type is being set coaxially also with Magnet 21.All field coil 22 is connected with power supply 28 with equal field coil, and constitutes and can be supplied with electric currents and make the magnetostatic field homogenization to equal field coil 22 with power supply 28 by equal field coil.
Gradient magnetic field coil assembly 23 is made of X-axis gradient magnetic field coil 23x, Y-axis gradient magnetic field coil 23y and Z axle gradient magnetic field coil 23z, and forms tubular at magnetostatic field with the inside of Magnet 21.Be provided with the platform 35 and become and videotape the zone of couching in the inside of gradient magnetic field coil assembly 23, and detected body P can be arranged on the platform 35 that couches.And, can not adopt RF coil 24 is arranged in the frame yet, and be arranged on the couch platform 35 and near the form of the composition of detected body P.
Gradient magnetic field coil assembly 23 is connected with power supply 27 with leaning magnetic field.X-axis gradient magnetic field coil 23x, Y-axis gradient magnetic field coil 23y in the gradient magnetic field coil assembly 23 and Z axle gradient magnetic field coil 23z are connected with power supply 27z with Z axle leaning magnetic field with power supply 27y with power supply 27x, Y-axis leaning magnetic field with the X-axis leaning magnetic field in the power supply 27 with leaning magnetic field respectively.
And, by respectively to X-axis gradient magnetic field coil 23x, Y-axis gradient magnetic field coil 23y and Z axle gradient magnetic field coil 23z supplying with electric current with power supply 27y and Z axle leaning magnetic field with power supply 27z with power supply 27x, Y-axis leaning magnetic field, can form the leaning magnetic field Gx of X-direction, the leaning magnetic field Gy of Y direction and the leaning magnetic field Gz of Z-direction respectively videotaping location by the X-axis leaning magnetic field.
Fig. 2 is the detailed pie graph of RF coil 24 shown in the presentation graphs 1 and signal receiver 30.
Fig. 3 is a WB coil 24a shown in the presentation graphs 2 and the profile schema diagram that profile instance is used of phased matrix coils 24b.
Each surface coils 24c of phased matrix coils 24b, around Z be configured in axisymmetrically the particular attention given position that comprises for example detected body P section L around.And, WB coil 24a is arranged on the outside of phased matrix coils 24b.RF coil 24 can send out high-frequency signal to detected body P by WB coil 24a, and can utilize each surface coils 24c of WB coil 24a or phased matrix coils 24b, receive the NMR signal that provides by the section L place that comprises the particular attention given position by multichannel, and then be sent to each receiving system loop 30a of each signal receiver 30.
On the other hand, the sequence signal controller 31 of control system 25 is connected with power supply 27, sender unit 29 and signal receiver 30 with leaning magnetic field.Sequence signal controller 31 has following function: to drive leaning magnetic field with power supply 27, sender unit 29 and signal receiver 30 needed control informations, describe such as being applied to intensity and the application time of leaning magnetic field, applying the function of the sequence signal information enforcement storage of action control informations such as timing with the pulse current at power supply 27 places; Sequence signal according to stored regulation is implemented to drive with power supply 27, sender unit 29 and signal receiver 30 to leaning magnetic field, to generate the function of X-axis leaning magnetic field Gx, Y-axis leaning magnetic field Gy, Z axle leaning magnetic field Gz and high-frequency signal.
And sequence signal controller 31 can also receive initial data (raw data) as the NMR signal behind the digitized from signal receiver 30, and is sent to computer 32.
Therefore, sender unit 29 has the control information that receives according to from sequence signal controller 31, high-frequency signal is sent to the function at RF coil 24 places, signal receiver 30 has: the NMR signal that is received by RF coil 24 is implemented needed signal processing and implemented the A/D conversion, generate the function as the initial data of the NMR signal behind the digitized thus; The initial data that is generated is sent to the function of sequence signal controller 31.
And, computer 32 can be by the mode of program being implemented read and move, and reconstructs image with data base 41, PAC and reconstructs with data base 42, WB and visually infer assembly 44, sensitivity map figure data base 45, pictorial data correction assembly 46, display process assembly 47 performance functions with data base 43, sensitivity distribution and reconstruct assembly 40, pictorial data as sensitivity prescan operating component 36, main scanning operating component 37, sequence signal controller Control Component 38, initial data with data base 39, image.Certainly, be not program, can also constitute computer 32 by specific circuit is set.
Sensitivity prescan operating component 36 has: in order to obtain the three-dimensional sensitivity map diagram data that distributes as the sensitivity of phased matrix coils 24b, and the sequence signal (sensitivity is inferred and use sequence signal) when implementing the sensitivity prescan is implemented the function of generation; The sensitivity that is generated inferred use sequence signal, be sent to sequence signal controller Control Component 38 to implement the function of sensitivity prescan.
Main scanning operating component 37 has: the various sequence signals that use during with the main scanning implementing to be used to obtain pictorial data are sent to sequence signal controller Control Component 38 to implement the function of main scanning.
Sequence signal controller Control Component 38 has: according to the information that is provided by input equipment 33 or other element, to be sent to sequence signal controller 31 and sentence the function of implementing sensitivity prescan or main scanning from the needed sequence signal the sequence signal that sensitivity prescan operating component 36 and main scanning operating component 37 receive.And, sequence signal controller Control Component 38 also has the initial data of reception from sequence signal controller 31 each the surface coils 24c by implementing collected WB coil 24a of sensitivity prescan or main scanning and phased matrix coils 24b, and it is configured in is formed on initial data with the function in the K space (fourier space) at data base 39 places.
Adopt this form of the composition, initial data can be implemented to store with data base 39 to each initial data of each WB coil 24a that generates in the signal receiver 30 and surface coils 24c.In other words be exactly that initial data is configured in the K space that is formed on initial data usefulness data base 39 places.
Image reconstructs assembly 40 to have: to being configured in the initial data of initial data with place, data base 39 K space by the operation main scanning, implement to reconstruct the function of processing with the pictorial data that reconstructs out detected body P such as Fourier transform images such as (FT); The pictorial data that reconstructs out is write to the function of pictorial data with data base 41.
And, image reconstructs assembly 40 also to have: to be configured in the initial data of initial data with data base 39 place, K space by operation sensitivity prescan, implement to reconstruct the identical mode of processing according to the initial data that the operation main scanning is obtained and implement to reconstruct processing, thereby, generate that PAC reconstructs image and WB reconstructs visual function according to the pictorial data of the detected body P that obtains respectively by phased matrix coils 24b and WB coil 24a; The PAC that is generated is reconstructed image and WB reconstructs image, write to PAC respectively and reconstruct image reconstructs visual usefulness data base 43 places with data base 42 and WB function.
Sensitivity distributes and to infer assembly 44 and have: use to be stored in PAC respectively and to reconstruct image and reconstruct image with data base 42 and WB and reconstruct visual with the PAC among the data base 43 and WB reconstructs image, produce the function of the three-dimensional sensitivity map diagram data of phased matrix coils 24b; Produced three-dimensional sensitivity map diagram data is write to the function of sensitivity map figure with data base 45 places.In other words be exactly that sensitivity distributes and to infer assembly 44 and have the function that the sensitivity map diagram data formation component as the sensitivity map diagram data that generates RF coil 24 uses.
Therefore, sensitivity distributes and to infer that assembly 44 has the 44a of threshold process portion, the zone suppresses handling part 44b, division arithmetic handling part 44c, the 44d of standardization portion, the data planarization 44e of portion, detected interior body region interpolation handling part 44f, detected external regional interpolation handling part 44g, bedding angle weighting handling part 44h, the three-dimensional smoothing processing 44i of portion.
The 44a of threshold process portion has PAC is reconstructed image and WB reconstructs the function that image is implemented threshold process, promptly has PAC is reconstructed image and WB to reconstruct the function that each signal intensity in the image shields smaller or equal to the partial data enforcement of pre-set threshold (comprising this threshold value) respectively.
The zone suppresses handling part 44b to have the PAC that uses when inferring by sensitivity is distributed and reconstructs zone after image and WB reconstruct visual threshold process, implementing the zone suppresses to handle, to be positioned at the smaller part of signal intensity of dwindling shielding area vicinity, back, the function of removing the data of when three-dimensional sensitivity map diagram data is made, using.
Division arithmetic handling part 44c has by reconstructing the PAC absolute value image of the signal absolute value of image as the PAC after threshold process and the zone inhibition processing, divided by the WB absolute value image of the signal absolute value that reconstructs image as WB, obtain function as the PAC absolute value image and the signal intensity between WB absolute value image of three-dimensional sensitivity map diagram data.
The 44d of standardization portion has the function that three-dimensional sensitivity map diagram data execution standardization is handled.
The data planarization 44e of portion has the transforming function transformation function of utilization to three-dimensional sensitivity map diagram data implementation data planarization, and the three-dimensional sensitivity map diagram data after utilizing inverse transform function to the data planarization is implemented to handle, to solve the function of the three-dimensional sensitivity map diagram data before the implementation data planarization.In other words be exactly, the data planarization 44e of portion has conduct and temporarily three-dimensional sensitivity map diagram data is transformed to the planarization distribution that is suitable for linear interpolation, and the three-dimensional sensitivity map diagram data after the linear interpolation processing is returned to the function of the data planarization assembly use of original distribution.Therefore, can with purpose accordingly will be arbitrarily function as this transforming function transformation function.
Detected interior body region interpolation handling part 44f has the no signal zone of conduct to the detected body P inside of three-dimensional sensitivity map diagram data, implements the function of the linear interpolation processing components use of linear interpolation processing.
Detected external regional interpolation handling part 44g has the no signal zone of conduct to the detected body P outside of three-dimensional sensitivity map diagram data, increases the function of handling the zone increase processing components use of implementing interpolation by the zone.
Bedding angle weighting handling part 44h has and can implement the function that weighting is handled to three-dimensional sensitivity map diagram data along the cutting bedding angle.
The three-dimensional smoothing processing 44i of portion has the function of using as the smoothing processing assembly of three-dimensional sensitivity map diagram data being implemented three-dimensional The disposal of gentle filter.
Pictorial data correction assembly 46 has: from being stored in sensitivity map figure with in three-dimensional sensitivity map diagram data of the data base 45, separate and pictorial data that the condition that videotapes, data collection condition, image when extracting out with the enforcement main scanning reconstruct condition etc. is obtained the function of the corresponding three-dimensional sensitivity map diagram data of condition; Use the three-dimensional sensitivity map diagram data that is extracted, to being stored in pictorial data is implemented correction with the brightness of the pictorial data at data base 41 places function by the operation main scanning.
Display process assembly 47 has will be stored in the pictorial data of pictorial data with data base 41 places, be sent to display device 34 and sentence the function of implementing demonstration.
Magnatic Resonance Imaging (MRI) apparatus 20 with above-mentioned form of the composition, as a whole, by the scanning operating component of each element as scannings such as enforcement such as main scanning and sensitivity prescans, the zone that the zone suppresses to handle is implemented in the signal area that is positioned at vicinity, no signal zone of the pictorial data that obtains by the sensitivity prescan suppress processing components, the pictorial data that use obtains by the sensitivity prescan generates the sensitivity map diagram data formation component of sensitivity map diagram data, and by bedding angle is weighted and its bedding angle weighting processing components of implementing to revise is brought into play function along cutting to sensitivity map diagram data.
Below, the effect of Magnatic Resonance Imaging (MRI) apparatus 20 is described.
The flow chart of the step when Fig. 4 uses 20 pairs of detected body P enforcement cross-sectional images of the Magnatic Resonance Imaging (MRI) apparatus shown in Fig. 1 to videotape for expression adds the reference number that numeral is arranged, each step in the expression flow process behind alphabetical S among the figure.
At first in step S10, by sensitivity prescan operating component 36 sensitivity is inferred with sequence signal and to be sent to sequence signal controller Control Component 7a place, before being used to obtain the main scanning of pictorial data, obtain the sensitivity prescan operation of the sensitivity map diagram data of phased matrix coils 24b earlier.
In other words be exactly, detected body P is set in advance on the platform 35 that couches, supply with electric current to videotape the regional magnetostatic field that forms to magnetostatic field with Magnet 21 with power supply 26 by magnetostatic field.And, supply with electric current so that be formed on the magnetostatic field homogenization that videotape location with power supply 28 to equal field coil 22 by equal field coil.
Subsequently, send action command from input equipment 33 to sequence signal controller Control Component 38.Sequence signal controller Control Component 38 is inferred sensitivity with sequence signal and is sent to sequence signal controller 31.Sequence signal controller 31 is inferred with sequence signal according to this sensitivity leaning magnetic field is implemented to drive with power supply 27, sender unit 29 and signal receiver 30, thereby form X-axis leaning magnetic field Gx, Y-axis leaning magnetic field Gy, Z axle leaning magnetic field Gz in the location that videotapes that is provided with detected body P, and produce high-frequency signal simultaneously.
At this moment, by X-axis leaning magnetic field Gx, Y-axis leaning magnetic field Gy, the Z axle leaning magnetic field Gz that gradient magnetic field coil produces, mainly be respectively as phase code (PE) with leaning magnetic field, read (RO) with leaning magnetic field, aspect encode (SE) use with leaning magnetic field.Therefore, on the rotation direction of the nuclear spin of the inside of detected body P, show systematicness, as the X coordinate and the Y coordinate of the two-dimensional position information in the aspect of utilizing SE to form along Z-direction with leaning magnetic field, be transformed to the phase changing capacity and the frequency variation of the nuclear spin of the detected body P inside that forms with leaning magnetic field with leaning magnetic field and RO by PE respectively.
Infer with sequence signal accordingly with high-frequency signal with sensitivity, be applied to the WB coil 24a of RF coil 24, and high-frequency signal is sent to detected body P from WB coil 24a from sender unit 29.And, at the inside of detected body P and the corresponding NMR signal that is included in the atomic nucleus nuclear magnetic resonance, NMR generation in the cutting aspect of frequency of high-frequency signal, by the WB coil 24a of RF coil 24 and each surface coils 24c of phased matrix coils 24b, be received and be sent to respectively each signal receiver 30 place by multichannel.
Each signal receiver 30 receives the NMR signal from each surface coils 24c of WB coil 24a and phased matrix coils 24b, and it is carried out such as various signal processing such as preposition amplification, intermediate frequency conversion, phase detection, low frequency amplification, filtering.Each signal receiver 30 also by the NMR signal being implemented the mode of A/D conversion, generates the initial data as the NMR signal of numerical data.Signal receiver 30 also is sent to the initial data that is generated sequence signal controller 31 places.
At this moment, reconstruct processing method to what the initial data collected by the sensitivity prescan was implemented, can be with main scanning in the identical method of processing method that reconstructs.If for instance, in main scanning, use the processing method that reconstructs that phased matrix coils 24b carries out, can be that the subduplicate Sum of Square that the pictorial data that obtains by each surface coils 24c is found the solution quadratic sum is handled (SoS processings) method, or to find the solution by the pictorial data of each surface coils 24c acquisition the signal intensity absolute value and reconstruct processing method.
Subsequently in step S11, sensitivity distributes and to infer assembly 44 and be stored in WB by utilization and reconstruct image and reconstruct image with data base 43 and PAC and reconstruct visual with the WB of each cutting aspect at data base 42 places and PAC reconstructs image, generates out three-dimensional sensitivity map diagram data.
Fig. 5 uses the Magnatic Resonance Imaging (MRI) apparatus 20 shown in Fig. 1 for expression, and the flow chart of the detailed step when generating sensitivity map diagram data adds the reference number that numeral is arranged, each step in the expression flow process behind alphabetical S among the figure.
At first in step S20, by the 44a of threshold process portion PAC is reconstructed image and WB and reconstruct image and implement threshold process, PAC is reconstructed each signal intensity that image and WB reconstruct image shield smaller or equal to the partial data enforcement of pre-set threshold (comprising this threshold value) respectively.Therefore, because being positioned at the signal intensity in the lobe of the lung and detected external body zone can be smaller or equal to threshold value (comprising this threshold value), so will be considered to that the PAC of the location in no signal zone reconstructs image and WB reconstructs image, from make the data that three-dimensional sensitivity map diagram data uses, get rid of.
Subsequently in step S21, suppress handling part 44b by the zone the distribute PAC that uses when inferring of sensitivity is reconstructed zone after the threshold process that image and WB reconstruct image and implements the zone and suppress to handle, will be arranged in the smaller part of the signal intensity that dwindles shielding area vicinity, back data of use when three-dimensional sensitivity map diagram data is made and remove.
Fig. 6 implements the figure that the zone suppresses an example of processing for representing by the Magnatic Resonance Imaging (MRI) apparatus shown in Fig. 1 20.
Implement that the PAC of zone before suppressing to handle reconstructs image and WB reconstructs image, have shown in Fig. 6 (a), passing threshold handles and implements the regional D1 of no signal after the shielding and signal area D2 is arranged.What be positioned near the position D1 of no signal zone has a signal area D2, can occur the smaller phenomenon of signal intensity usually.Because sensitivity prescan that the phased matrix coils 24b of use implements and the sensitivity prescan that uses WB to reconstruct image enforcement are implemented respectively, so produced the occasion of position deviation for internal organs of detected body P etc., if intactly use PAC to reconstruct image and WB reconstructs visual signal intensity ratio, then the discontinuous phenomenon of signal intensity can appear in the signal area D2 that has of position near the D1 of territory, dead space being arranged in.
Therefore, the part D2 ' that is positioned near the position of D1, no signal zone among the D2 of signal area that has shown in Fig. 6 (b) is replaced into the no signal zone, signal area D2 is arranged thereby dwindle.Adopt this mode, PAC can be reconstructed image and WB reconstruct in the image be positioned near the signal intensity of the position D1 of no signal zone smaller signal area D2 arranged, remove the data of use when three-dimensional sensitivity map diagram data is made.
Subsequently in step S22, by division arithmetic handling part 44e by will implement after suppress to handle in threshold process and zone each cutting aspect reconstruct the PAC absolute value image of the signal absolute value of image as PAC, divided by the WB absolute value image of the signal absolute value that reconstructs image as WB, thereby obtain as the PAC absolute value image of three-dimensional sensitivity map diagram data and the signal intensity ratio between WB absolute value image.
In step S23,, handle subsequently by each cutting aspect execution standardization by the three-dimensional sensitivity map diagram data of the 44d of standardization portion to solving as the signal intensity ratio between PAC absolute value image and WB absolute value image.
Subsequently in step S24, the 44e of portion utilizes transforming function transformation function by the data planarization, three-dimensional sensitivity map diagram data implementation data planarization to after the execution standardization processing is transformed to the planarization data that are suitable for carrying out linear interpolation with three-dimensional sensitivity map diagram data.If for instance, can adopt such as arbitrary functions such as n function, exponential function, logarithmic functions, to the match of three-dimensional sensitivity map diagram data implementation data, and implement suitable processing according to reducing the mode that local data that linear interpolation is exerted an influence rises and falls.
Subsequently in step S25,, implement linear interpolation and handle by the no signal zone that is positioned at the inner place of detected body P in the three-dimensional sensitivity map diagram data of detected interior body region interpolation handling part 44f after to the implementation data planarization.
Fig. 7 is that expression is by the Magnatic Resonance Imaging (MRI) apparatus 20 shown in Fig. 1, to the regional figure that implements an example of linear interpolation processing of the no signal of the detected body P of being positioned at of three-dimensional sensitivity map diagram data inside.
The figure of an example when Fig. 7 (a) sees three-dimensional sensitivity map diagram data for expression along the cutting bedding angle, Fig. 7 (b) is the figure of the example of expression when the PE bedding angle is seen three-dimensional sensitivity map diagram data.Three-dimensional sensitivity map diagram data after execution standardization processing and the data planarization has no signal zone D1 and signal area D2 is arranged.And no signal zone D1 is made of no signal zone D1a that is positioned at detected body P inside and the no signal zone D1b that is positioned at detected body P outside.
Detected interior body region interpolation handling part 44f is shown in the arrow among Fig. 7 (b), to being positioned at the no signal zone D1a of detected body P inside, by using straight line, implement linear interpolation and handle implementing ways of connecting such as the signal strength values among the D2 of signal area that has along the RO directional profile.Adopt this mode, the no signal zone D1a that is positioned at detected body P inside can be replaced into signal area D2.
And linear interpolation is handled and is not limited in the direction along RO, can also be along carrying out such as any directions such as PE direction, SL directions.
Subsequently in step S26, to implementing the three-dimensional sensitivity map diagram data after linear interpolation is handled, utilize the inverse conversion function that it is converted to state before the implementation data planarization once more by the data planarization 44e of portion.
In step S27, to the no signal zone that is positioned at detected body P outside in the three-dimensional sensitivity map diagram data, implement interpolation by the mode of implementing zone increase processing and handle subsequently by detected external regional interpolation handling part 44g.
Fig. 8 implements key diagram that zone increase the method occasion handled under by 26 methods to the no signal zone of the detected body P of being positioned at of three-dimensional sensitivity map diagram data outside for explanation, and Fig. 9 implements key diagram that zone increase the method occasion handled under by 6 point methods to the no signal zone of the detected body P of being positioned at of three-dimensional sensitivity map diagram data outside for explanation.
It is that a kind of usefulness has the value at place, signal area intactly the value at place, no signal zone to be implemented metathetical processing method that the zone increases processing.If for instance, adopt the zone of 26 point methods to increase processing as shown in Figure 8, for the signal intensity of grid mid point A the signal area that has more than or equal to threshold value (comprising this threshold value), and, use the signal intensity enforcement replacement Treatment of the signal intensity at mid point A place to 26 lattice point places in no signal zone with each signal intensitys of 26 lattice points of this mid point A adjacency occasion smaller or equal to the no signal zone of threshold value (comprising this threshold value).
Adopt the zone of 6 point methods to increase processing as shown in Figure 9, for the signal intensity of grid mid point A the signal area that has more than or equal to threshold value (comprising this threshold value), and, use the signal intensity enforcement replacement Treatment of the signal intensity at mid point A place to 6 lattice point places in no signal zone with each signal intensitys of 6 lattice points of this mid point A adjacency occasion smaller or equal to the no signal zone of threshold value (comprising this threshold value).
Figure 10 passes through the Magnatic Resonance Imaging (MRI) apparatus 20 shown in Fig. 1 for expression, and the figure that the zone increases an example of processing is implemented in the no signal zone of the detected body P of being positioned at of three-dimensional sensitivity map diagram data outside.
Implement three-dimensional sensitivity map diagram data after linear interpolation is handled shown in Figure 10 (a), what have the no signal zone D1 that is positioned at detected body P outside and be positioned at detected body P inside has a signal area D2.The result who the no signal zone D1 that is positioned at detected body P outside is implemented zone increase processing is, shown in Figure 10 (b), the no signal zone D1 that will be positioned at detected body P outside has been replaced into signal area D2 and has implemented the interpolation processing, makes Zone Full be signal area D2.And, the All Ranges of each cutting aspect is all produced three-dimensional sensitivity map diagram data.
According to the channel configuration form of phased matrix coils 24b, the Z-direction (bedding angle) that the sensitivity of phased matrix coils 24b is distributed in the erection seat mark system goes up possible different.
Therefore in step S28, by bedding angle weighting handling part 44h by three-dimensional sensitivity map diagram data is weighted and it is implemented to revise along the cutting bedding angle.Bedding angle weighting handling part 44h can find the solution the Y enforcement reciprocal of correction factor, and then by correction factor 1/Y being multiply by three-dimensional sensitivity map diagram data, come it along cutting aspect weighted direction by such as formula (1).
Y＝1 if?Z＜B (1)
Y＝A×(A-B)
2+1 if?Z≥B
Wherein, Z: along the aspect position of Z direction
A: coefficient
B: side-play amount
Figure 11 uses the Magnatic Resonance Imaging (MRI) apparatus 20 shown in Fig. 1 for expression, to the curve chart of the correction factor 1/Y of three-dimensional sensitivity map diagram data when the cutting bedding angle is implemented weighting and handled.
The longitudinal axis among Figure 11 is represented correction factor 1/Y, and transverse axis is represented the aspect position Z along the Z direction.And, the curve of the correction factor 1/Y the when solid line among Figure 11 is represented in the formula (1) coefficient A=-20, side-play amount B=0.
In other words be exactly,, be set to correction factor 1/Y=1, and three-dimensional sensitivity map diagram data is not implemented to revise for along the aspect position Z of the Z direction occasion littler than predetermined side-play amount B=0.
On the other hand, for along the aspect position Z of Z direction more than or equal to the predetermined side-play amount B=0 occasion of (comprising 0), utilize the computing formula of quadratic function that correction factor 1/Y is implemented to calculate, and then multiply by three-dimensional sensitivity map diagram data and it is implemented correction by institute being obtained correction factor 1/Y.
Yet the computing formula that the Y enforcement reciprocal of correction factor is calculated also can not adopt quadratic function, but adopts other arbitrary function to implement approximate processing.
In step S29, three-dimensional sensitivity map diagram data is implemented 3D The disposal of gentle filter suitable, that have needed intensity subsequently by the three-dimensional smoothing processing 44i of portion.Adopt this mode, can remove the extremely big position of value of localized positions, thereby can generate final three-dimensional sensitivity map diagram data accurately along improving seriality on all directions of RO direction, PE direction, SL direction.
In step S30, will distribute by sensitivity and infer the three-dimensional sensitivity map diagram data that assembly 44 generates subsequently, write and be stored in sensitivity map figure data base 45 places.
In the step S12 of Fig. 4, image is obtained to be sent to sequence signal controller Control Component 38 places with sequence signal subsequently, carry out main scanning by main scanning operating component 37.And, implement the mode that image reconstructs processing by reconstruct 40 pairs of collected initial datas of assembly by image, obtain pictorial data.
Subsequently in step S13, use three-dimensional sensitivity map diagram data that the brightness of the pictorial data that obtains by main scanning is implemented to revise.Adopt this mode, can according to main scanning in videotape terms and conditions that condition, data collection condition, image reconstruct condition etc. accordingly such as videotaping profile direction, spatial resolution etc., by pictorial data correction assembly 46 from sensitivity map figure with obtaining out corresponding three-dimensional sensitivity map diagram data the data base 45.
And pictorial data correction assembly 46 uses the three-dimensional sensitivity map diagram data that obtains out, and the brightness of pictorial data is implemented to revise.At this moment can also as required the three-dimensional sensitivity map diagram data execution standardization that is obtained out be handled.
Adopt this form of the composition, can suppress the influence of the signal intensity inhomogeneities of generation because the sensitivity of phased matrix coils 24b disperses, thus the pictorial data after the brightness that can be improved.
If adopt Magnatic Resonance Imaging (MRI) apparatus 20 with above-mentioned form of the composition, can be according to implementing the pictorial data that the sensitivity prescan is obtained, the sensitivity distribution of more phased matrix coils 24b is implemented to infer, and then can distribute according to the sensitivity of the phased matrix coils 24b that is obtained, to implementing better correction by the brightness of implementing the pictorial data that main scanning obtained.
Belong to the pictorial data brightness correction method of the Magnatic Resonance Imaging (MRI) apparatus 1 of technology formerly for use, can't implement enough various occasions of correction to the brightness of pictorial data, such as videotape the occasion that includes in the zone such as the no signal zone of lung etc. at the sensitivity prescan, because with the thinking of detected body P internal organs change of shape irrespectively, and when implementing the sensitivity prescan and videotape, implement to videotape generation occasion devious between the shape of shape and the detected body P that implements to videotape acquisition by WB coil 24a of detected body P of acquisition by phased matrix coils 24b, and because each channel configuration property of phased matrix coils 24b, can produce the occasion of signal intensity inhomogeneities along the Z-direction of device coordinate system, if adopt Magnatic Resonance Imaging (MRI) apparatus 20 then can implement good correction to the brightness of pictorial data.
Figure 12 uses the sketch map of the cross-sectional image of the detected body P after the brightness correction that the Magnatic Resonance Imaging (MRI) apparatus 20 shown in Fig. 1 obtains for expression, the sketch map of the cross-sectional image of the detected body P after the brightness correction that Figure 13 obtains for the Magnatic Resonance Imaging (MRI) apparatus 20 in the expression priority of use technology.
As shown in Figure 13, when implementing the sensitivity prescan and videotape, implement to videotape between the shape of shape and the detected body P that implements to videotape acquisition by WB coil 24a of detected body P of acquisition producing when deviation is arranged by phased matrix coils 24b, can't be to the good correction of brightness enforcement of pictorial data.
On the other hand, as shown in Figure 12, reconstruct the mode that image enforcement zone inhibition is handled by WB being reconstructed image and PAC, when even generation has deviation between the shape of the shape of the detected body P that implements to videotape acquisition by phased matrix coils 24b and the detected body P that implements to videotape acquisition by WB coil 24a, also can generate the three-dimensional sensitivity map diagram data that improves after the seriality accurately, thereby can implement good correction the brightness of pictorial data.
And, in having the Magnatic Resonance Imaging (MRI) apparatus 20 of the form of the composition as mentioned above, the part in also can the omitted data processing procedure, and omit and the element of this part correlation in a part.And, can also replace phased matrix coils 24b, but adopt the form of the composition of single coil.
Figure 14 is the functional-block diagram of second form of implementation of expression Magnatic Resonance Imaging (MRI) apparatus of the present invention.
Magnatic Resonance Imaging (MRI) apparatus 20A as shown in figure 14, the function that the concrete form of the composition of its RF coil 24 and signal receiver 30 and computer 32 are had is different with as shown in Figure 1 Magnatic Resonance Imaging (MRI) apparatus 20.Other element is all identical in fact with as shown in Figure 1 Magnatic Resonance Imaging (MRI) apparatus 20 with effect, so adopts and be denoted by like references identical component part, and has omitted the detailed description to these parts.
Figure 15 is the detailed pie graph of an example of RF coil 24 shown in expression Figure 14 and signal receiver 30.
The coil phased matrix coils 24b that use, that become main coil that RF coil 24 is implemented to receive by the WB coil 24a that high-frequency signal implement is sent usefulness, NMR signal as to main scanning the time constitutes.Phased matrix coils 24b has a plurality of surface coils 24c.
The concrete configuration form of WB coil 24a and phased matrix coils 24b is identical with the form of the composition as shown in Figure 3.
In other words be exactly that each surface coils 24c at phased matrix coils 24b place for example is configured in around the section L at the particular attention given position that comprises detected body P axisymmetrically around Z.And, WB coil 24a is arranged on the outside of phased matrix coils 24b.RF coil 24 constitutes by WB coil 24a and sends out high-frequency signal to detected body P, and utilize each surface coils 24c of phased matrix coils 24b, by multichannel the NMR signal that provides from the section L that comprises the particular attention given position is implemented signal and receive, and then be sent to each signal receiver 30.
In addition, the mode of computer 32 by program being implemented read and move reconstructs assembly 40, pictorial data as sensitivity prescan operating component 36, sensitivity prescan condition enactment assembly 50, main scanning operating component 37, sequence signal controller Control Component 38, initial data with data base 39, image and infers assembly 44, sensitivity map figure usefulness data base 45, pictorial data correction assembly 46, display process assembly 47 and the performance function with data base 41, main coil image with data base 51, sensitivity distribution.Certainly, also can not adopt program mode (PM), but constitute this computer 32 by specific loop design.
Sensitivity prescan operating component 36 has: according to the condition that videotapes that receives from sensitivity prescan condition enactment assembly 50, the sequence signal (sensitivity is inferred and use sequence signal) when the three-dimensional sensitivity map diagram data that distributes for the sensitivity of obtaining as phased matrix coils 24b is implemented the sensitivity prescan is implemented the function of generation; The sensitivity that is generated inferred with sequence signal be sent to sequence signal controller Control Component 38 to implement the function of sensitivity prescan.
Sensitivity prescan condition enactment assembly 50 has: according to making the fully low mode of contrast in order to find the solution three-dimensional sensitivity map diagram data, the condition that videotapes during to the sensitivity prescan is implemented the function of setting; The sensitivity prescan condition of videotaping that sets is sent to the function at sensitivity prescan operating component 36 places.
The various sequence signals that main scanning operating component 37 uses when having the main scanning that execution is used to obtain pictorial data are sent to sequence signal controller Control Component 38 to implement the function of main scanning.
Sequence signal controller Control Component 38 has the information that provides according to by input equipment 33 or other element, will be from the sequence signal that sensitivity prescan operating component 36 and main scanning operating component 37 receive needed sequence signal, be sent to sequence signal controller 31 and sentence the function of implementing sensitivity prescan or main scanning.And, sequence signal controller Control Component 38 also has the initial data of reception by sequence signal controller 31 each the surface coils 24c by implementing the collected phased matrix coils 24b of sensitivity prescan or main scanning, and it is configured in is formed on the function that initial data is located with the K space (fourier space) at data base 39 places.
Therefore, each initial data of each surface coils 24c of generating in signal receiver 30 with 39 couples of data bases of initial data is implemented to store.In other words be exactly initial data to be configured in the place, K space that is formed among the initial data usefulness data base 39.
Image reconstructs assembly 40 to have: to being configured in the initial data of initial data with place, data base 39 K space by the operation main scanning, implement to reconstruct the function of processing with the pictorial data that reconstructs out detected body P such as Fourier transform images such as (FT); The pictorial data that reconstructs out is write to the function of pictorial data with data base 41 places.
And, image reconstructs assembly 40 also to have: to be configured in the initial data of initial data with data base 39 place, K space by operation sensitivity prescan, implement to reconstruct the identical mode of processing according to the initial data that the operation main scanning is obtained and implement to reconstruct processing, the pictorial data of detected body P is implemented to reconstruct the function of processing as the main coil pictorial data; The main coil pictorial data that reconstructs out is write to the function of main coil image with data base 51.
The sensitivity distribution is inferred assembly 44 and is had: by being stored in the main coil pictorial data of main coil image with data base 51 places, infer with the data use with the sensitivity of initial data as constituting the sensitivity correction, thereby produce as the function of sensitivity correction with the three-dimensional sensitivity map diagram data of the phased matrix coils 24b of data; Produced three-dimensional sensitivity map diagram data is write to the function of sensitivity map figure with data base 45 places.Sensitivity distributes and to infer that assembly 44 has the 44j of threshold process portion, the zone dwindles the 44k of portion, interpolation handling part 44l, the 44m of smoothing processing portion.
The 44j of threshold process portion has the function of the main coil pictorial data being implemented threshold process, promptly has the function of the signal intensity of main coil pictorial data being implemented shielding smaller or equal to the data at the part place of pre-set threshold (comprising this threshold value).
The zone dwindles the 44k of portion to have and implements to dwindle processing, the function of removing the data that the part that the signal intensity of shielding area vicinity is smaller is used to implementing the distribute zone of the main coil pictorial data used when inferring of sensitivity when three-dimensional sensitivity map diagram data is made.
Interpolation handling part 44l has by extrapolation process or interpolation processing, to implement as the main coil pictorial data zone dwindle handle the back conductively-closed the no signal zone in three-dimensional sensitivity map diagram data implement the mode of inferring, the distribute main coil pictorial data of inferring usefulness of sensitivity is implemented the function of interpolation.
The 44m of smoothing processing portion has sensitivity distributed and infers the main coil pictorial data of usefulness, implements smoothing processing to produce the function of final three-dimensional sensitivity map diagram data.
Pictorial data correction assembly 46 has: obtain the function of the corresponding three-dimensional sensitivity map diagram data of condition from being stored in sensitivity map figure with in three-dimensional sensitivity map diagram data of the data base 45, separating pictorial data that the condition that videotapes, data collection condition, the image that extract when implementing main scanning reconstruct condition etc.; Use the three-dimensional sensitivity map diagram data that is extracted, to pictorial data is implemented correction with the signal intensity of the pictorial data at data base 41 places the function that is stored in that obtains by the operation main scanning.
Display process assembly 47 has will be stored in the pictorial data of pictorial data with data base 41 places, be sent to display device 34 and sentence the function of implementing demonstration.
Magnatic Resonance Imaging (MRI) apparatus 20A with above-mentioned form of the composition, as a whole, each element has signal receiving coil when image is videotaped as signal receiving coil, and carry out that the sensitivity correction be used for generating the signal receiving coil when implementing main scan image and videotaping with the scanning operating component of the sensitivity prescan of data, only will implement that the image of sensitivity prescan videotapes by the data of signal receiving coil acquisition as initial data, and the function that the sensitivity correction of generation sensitivity correction data is used with the data formation component.
Figure 16 uses the Magnatic Resonance Imaging (MRI) apparatus 20A shown in Figure 14 for expression, and the flow chart of the step when detected body P enforcement cross-sectional image is videotaped adds the reference number that numeral is arranged, each step in the expression flow process behind alphabetical S among the figure.
At first in step S40, move the operation of sensitivity prescan.The condition of videotaping of 50 pairs of sensitivity prescans of sensitivity prescan condition enactment assembly is provided with, and sensitivity inferred with sequence signal is sent to sensitivity prescan operating component 36 places.At this, be to make to carry out in order to make three-dimensional sensitivity map diagram data to reconstruct and handle the image that obtains and have fully low contrast the condition setting that videotapes of sensitivity prescan.
If for instance, the condition that videotapes of low contrast, can be set at by prolonging the mode of repetition time (TR:repetition time) and shortening echo time (TE:echo time), make the condition when all smaller proton density of any one influence among T1 (vertical relaxation time) and the T2 (horizontal relaxation time) emphasized that image videotapes, or with the akin condition that videotapes of this condition.
If for instance, the sensitivity that enforcement sensitivity prescan is used is inferred and is used sequence signal, can be when high speed Fourier echo (FFE) type sequence signal, TE to be set at about relatively shorter 1-5 millisecond (ms), the signal when (flip) angle of will reversing is set at 5～10 smaller degree left and right sides.And, when TR is 200 milliseconds of (ms) left and right sides, can be to implementing to collect more than or equal to the main coil pictorial data of the cutting aspect of 20 width of cloth (comprising 20 width of cloth), and then can obtain to have reflected the main coil pictorial data of the whole volume of the sensitivity of making the needed surface coils 24c of three-dimensional sensitivity map diagram data.
On the other hand, videotaping of sensitivity prescan can be to videotaping that the multiple cutting aspect of 2D is carried out, and also can videotape for 3D.Sensitivity when enforcement 3D videotapes is inferred and is used sequence signal, for example can adopt in FFE type sequence signal TE is set at about relatively shorter 1-5 millisecond (ms), and (flip) angle of will reversing is set at the smaller signals smaller or equal to 5 degree (comprising 5 spends).And, when TR is 10 milliseconds of (ms) left and right sides, can videotape the needed main coil pictorial data of acquisition in the same time with 2D.
By sensitivity prescan operating component 36 sensitivity is inferred with sequence signal and to be sent to sequence signal controller Control Component 38 places, and the phased matrix coils 24b of the signal receiving coil (main coil) only will implement main scanning the time implements the sensitivity prescan as the signal receiving coil.In other words be exactly before obtaining the main scanning that pictorial data uses, to be used to obtain the sensitivity prescan operation of the sensitivity map diagram data of phased matrix coils 24b earlier.
Detected body P is set in advance on the platform 35 that couches, supply with electric current to videotape regional form magnetostatic field to magnetostatic field with Magnet 21 with power supply 26 by magnetostatic field.And, supply with electric current with power supply 28 to equal field coil 22 by equal field coil, so that be formed on the magnetostatic field homogenization that videotapes location.
Subsequently, send action command by input equipment 33 to sequence signal controller Control Component 38.When receiving this instruction, sequence signal controller Control Component 38 is inferred sensitivity with sequence signal and is sent to sequence signal controller 31.Sequence signal controller 31 is inferred with sequence signal according to this sensitivity leaning magnetic field is implemented to drive with power supply 27, sender unit 29 and signal receiver 30, thereby form X-axis leaning magnetic field Gx, Y-axis leaning magnetic field Gy, Z axle leaning magnetic field Gz in the location that videotapes that is provided with detected body P, and produce high-frequency signal simultaneously.
At this moment, by X-axis leaning magnetic field Gx, Y-axis leaning magnetic field Gy, the Z axle leaning magnetic field Gz that gradient magnetic field coil produces, mainly be respectively as phase code (PE) with leaning magnetic field, read (RO) with leaning magnetic field, aspect encode (SE) use with leaning magnetic field.Therefore, the nuclear spin of the inside of detected body P in rotational direction shows systematicness, as utilizing SE X coordinate and the Y coordinate of leaning magnetic field, be transformed to the phase changing capacity and the frequency variation of the nuclear spin of detected body P inside respectively with leaning magnetic field with leaning magnetic field and RO by PE along the two-dimensional position information in the aspect of Z-direction formation.
Infer the WB coil 24a that accordingly high-frequency signal is applied to RF coil 24 with sequence signal from sender unit 29 and sensitivity, and high-frequency signal is sent to detected body P from WB coil 24a.And, at the inside of detected body P and the corresponding NMR signal that is included in the atomic nucleus magnetic resonance generation in the cutting aspect of frequency of high-frequency signal, by RF coil 24, as each surface coils 24c of the phased matrix coils 24b of main coil, be received and be sent to respectively each signal receiver 30 place by multichannel.
And WB coil 24a can only be used for high-frequency signal is implemented to send, and is not used in the reception operation of signal.
Each signal receiver 30 receives the NMR signal from each surface coils 24c of phased matrix coils 24b, and carries out the various signal processing such as preposition amplification, intermediate frequency conversion, phase detection, low frequency amplification, filtering etc.Each signal receiver 30 also by the NMR signal being implemented the mode of A/D conversion, generates the initial data as the NMR signal of numerical data.Signal receiver 30 also is sent to the initial data that is generated sequence signal controller 31 places.
At this moment, reconstruct processing method to what the initial data collected by the sensitivity prescan was implemented, be with main scanning in the identical method of processing method that reconstructs.If for instance, in main scanning, use the processing method that reconstructs that phased matrix coils 24b carries out, can handle for the subduplicate Sum of Square that the pictorial data that obtains by each surface coils 24c is found the solution quadratic sum (SoS processings) method and to find the solution by the pictorial data of each surface coils 24c acquisition the signal intensity absolute value and reconstruct processing method etc.
Subsequently in step S41, sensitivity distributes and infers assembly 44 and infer with data as sensitivity with the main coil pictorial data that becomes volume data at data base 51 places and use by being stored in the main coil image, and the enforcement that distributes is inferred to sensitivity.
Figure 17 is illustrated in the indicative flowchart shown in Figure 16, the sensitivity of phased matrix coils 24b is distributed implements to push away the flow chart of periodic step, among the figure behind alphabetical S the additional reference number that numeral is arranged, each step in the expression flow process.
At first in step S50, the main coil pictorial data is read to the sensitivity distribution from the main coil image with data base 51 infer assembly 44.
Figure 18 is illustrated in the sketch map that low contrast videotapes the signal intensity profile of the main coil pictorial data that obtains under the condition, and Figure 19 is illustrated in the sketch map that conventional contrast videotapes the signal intensity profile of the main coil pictorial data that obtains under the condition.
In Figure 18 and Figure 19, the longitudinal axis is represented the signal value of main coil pictorial data, and transverse axis represents to comprise the position of the section L direction of region-of-interest (ROI:region of interest) as shown in Figure 3.
As shown in Figure 19, for having the main coil pictorial data that obtains under the condition that videotapes of conventional contrast, because the different influences that produce of contrast are not fully little, so be difficult to intactly infer with data as the sensitivity of phased matrix coils 24b use.
On the other hand, as shown in Figure 18, for the main coil pictorial data that obtains under videotaping condition at low contrast, because the different influences that produce of contrast are fully little, even use so intactly infer with data as the sensitivity of phased matrix coils 24b, the error that is produced is also quite little.
And at this, the main coil pictorial data is described as the one-dimensional data on the straight line L that comprises ROI, adopt enforcement two dimension or three-dimensional to videotape yet in fact also can constitute, two dimension or three-dimensional main coil pictorial data are inferred with the data use as sensitivity, make the various process object that three-dimensional sensitivity map diagram data is used.
Therefore, the main coil pictorial data that will obtain under the condition that videotapes of low contrast is inferred with data as sensitivity and is used, and implements to be used to make the needed various processing operations of three-dimensional sensitivity map diagram data.Below, the manufacture method of the sensitivity map diagram data in the technology is formerly compared explanation.
The sketch map of the data that Figure 20 is generated during three-dimensional sensitivity map diagram data for the Magnatic Resonance Imaging (MRI) apparatus in the expression priority of use technology 1 generates.
Belong to the Magnatic Resonance Imaging (MRI) apparatus 1 of technology formerly, for phased matrix coils 24b and WB coil 24a are all implemented the sensitivity prescan as the signal receiving coil, and with shown in Figure 20 (a) pass through main coil pictorial data that phased matrix coils 24b obtains, these two data of WB circuit diagram image data of passing through WB coil 24a acquisition shown in Figure 20 (b) are all inferred with data as sensitivity and are used.And, by being compared, main coil pictorial data and WB circuit diagram image data both sides and pre-set threshold ε, ε ' implement threshold process, no signal zone part is inferred with removing in the data by sensitivity.
Infer with the main coil pictorial data among the D1 of data area divided by WB circuit diagram image data by implementing sensitivity after the threshold process, produce the three-dimensional sensitivity map diagram data after the nothing dimensionization shown in Figure 20 (c).And the interpolation processing by to whole zone enforcement extrapolation process or interpolation processing etc. comes three-dimensional sensitivity map diagram data is implemented to infer, and then produces the three-dimensional sensitivity map diagram data shown in Figure 20 (d).
On the other hand, Magnatic Resonance Imaging (MRI) apparatus 20A as shown in figure 14 can only adopt phased matrix coils 24b to implement the sensitivity prescan as the signal receiving coil.
The key diagram of existing problem when Figure 21 generates for the Magnatic Resonance Imaging (MRI) apparatus 20A shown in explanation use Figure 14 implements three-dimensional sensitivity map diagram data, Figure 22 for expression by can avoiding the step of problem as shown in figure 21, use Magnatic Resonance Imaging (MRI) apparatus 20A to implement the sketch map of the data that generated when three-dimensional sensitivity map diagram data generates.
In other words be exactly that in step S51 as shown in figure 17, passing threshold handling part 44j implements threshold process to the main coil pictorial data.Promptly, shown in Figure 21 (a) and shown in Figure 22 (a), signal intensity in the main coil pictorial data is implemented shielding smaller or equal to the partial data of pre-set threshold ε (until equating with this threshold epsilon), with outside the zone that will be positioned at detected body P and the part in the no signal zone of pulmonary etc., infer with removing the data from sensitivity.
Main coil pictorial data for the low contrast of emphasizing image etc. such as proton density, sensitivity after implementing threshold process is inferred with can WB circuit diagram image data not being implemented division arithmetic among the D1 of data area, use and it is intactly inferred with data as sensitivity, but iff implementing threshold process, near the relatively influence of lower part of the signal intensity of the position no signal zone that do not eliminate outside the zone that is positioned at detected body P shown in Figure 21 (b) and pulmonary etc. provides, then sensitivity is inferred and is used the value of data smaller, will be difficult to three-dimensional sensitivity map diagram data is implemented correct the making.
Therefore in step S52, dwindle the 44k of portion by the zone and implement to dwindle processing infer the zone of using as sensitivity with data.In other words be exactly; infer near the position of boundary portion of the shielding area of using data area D1 as Figure 22 (b) sensitivity that is shown in; the little phenomenon of signal intensity ratio other parts can appear usually; so implement to dwindle processing by sensitivity being inferred, remove the zone of the little marginal portion of signal intensity with data area D1.
Subsequently in step S53, shown in Figure 22 (c), dwindle new sensitivity after the processing and infer signal intensity with the main coil pictorial data among the D2 of data area with implementing the zone, regard three-dimensional sensitivity map diagram data as.And, implement the interpolation of extrapolation process or interpolation processing etc. handles by interpolation handling part 44l, come to implement the zone dwindle conductively-closed after the processing the no signal zone in three-dimensional sensitivity map diagram data implement to infer, produce the three-dimensional sensitivity map diagram data in the whole zone shown in Figure 22 (d).
Subsequently in step S54, by the three-dimensional sensitivity map diagram data in the whole zone after interpolation is handled, carry out handling such as the data fitting of orthogonal expansion etc., implement smoothing processing.Adopt this mode, finally produce the good three-dimensional sensitivity map diagram data of seriality.
And, in step S42 shown in Figure 16, the three-dimensional sensitivity map diagram data of phased matrix coils 24b is stored in sensitivity map figure with data base 45 places.
Subsequently in step S43, image obtained with sequence signal be sent to sequence signal controller Control Component 38 places by main scanning operating component 37, phased matrix coils 24b is implemented the main scanning operation as the signal receiving coil.Then, collect initial data and reconstruct assembly 40 and implement images and reconstruct processing, obtain pictorial data by image.
Subsequently in step S44, according to main scanning in videotape the corresponding mode of terms and conditions that condition, data collection condition, image reconstruct condition etc. such as videotaping profile direction, spatial resolution etc., by pictorial data correction assembly 46 from sensitivity map figure with obtaining corresponding three-dimensional sensitivity map diagram data the data base 45.
In step S45,, pictorial data is implemented to revise subsequently by the three-dimensional sensitivity map diagram data that 46 uses of pictorial data correction assembly obtain.In other words be exactly, multiply by the mode of each signal intensity of pictorial data, implement correcting process by inverse with three-dimensional sensitivity map diagram data.At this moment, can also suitably make the processing of the non-pulverised of three-dimensional sensitivity map diagram data, or be zero occasion, the fault processing of the various routines of the pictorial data correction of carrying out that such as occasion classification is handled etc. for three-dimensional sensitivity map diagram data.
Adopt this form of the composition, the influence of the signal intensity inhomogeneities of the generation of can dispersing to the sensitivity owing to phased matrix coils 24b is implemented to suppress, and can obtain the pictorial data after the image quality enforcement improvement.
If adopt Magnatic Resonance Imaging (MRI) apparatus 20A with above-mentioned form of the composition, then can adopt the phased matrix coils 24b that is made of a plurality of surface coils to carry out image videotapes, even the sensitivity of signal receiving coil produces discrete, because not with the signal receiving coil of WB coil 24a when implementing the sensitivity prescan, so can be in the shorter time according to videotaping the mode of conditional independence with visual kind etc., the signal intensity of pictorial data risen and fallen implements to revise.And, compare with technology formerly, can be easily obtain at the whole image that all has within sweep of the eye than higher diagnosis capability that videotapes having under the condition of good accuracy.
If for instance, for being under the condition that videotapes of 200 milliseconds (ms) at aforesaid TR, when the matrix to 48 * 48 is implemented to videotape, formerly in the technology in order when implementing the sensitivity prescan, to obtain the data of WB coil 24a and phased matrix coils 24b, the time of videotaping is 19.2 seconds, if yet adopt Magnatic Resonance Imaging (MRI) apparatus 20A, by time at half, feel suffocated in promptly 9.6 seconds and videotape, just can obtain to make the needed all essential main coil pictorial data of three-dimensional sensitivity map diagram data, therefore can with videotape time decreased half, thereby can reduce patient's burden.
And, when adopting this method owing to do not need to use videotaping of WB coil 24a, so can not move under the state fully in the decoupling of WB coil 24a and phased matrix coils 24b, and can prevent the mistake of Data Position deviation between WB coil 24a and phased matrix coils 24b etc.
Figure 23 is the functional-block diagram of the 3rd form of implementation of expression Magnatic Resonance Imaging (MRI) apparatus of the present invention.
Magnatic Resonance Imaging (MRI) apparatus 20B as shown in figure 23, the function aspects of using with photography conditions assignment component 60 as all (shimming) at computer 32 is different with as shown in figure 14 Magnatic Resonance Imaging (MRI) apparatus 20A.Other element is all identical in fact with as shown in figure 14 Magnatic Resonance Imaging (MRI) apparatus 20A with effect, so adopts and be denoted by like references identical component part, and has omitted the detailed description to these parts.
The computer 32 of Magnatic Resonance Imaging (MRI) apparatus 20B, also having can be as equal the function of using with photography conditions assignment component 60.All the field has equal the condition that the videotapes enforcement setting of handling for magnetostatic field spatial non-uniformity enforcement correction is carried out with photography conditions assignment component 60, and is sent to the function at sensitivity prescan operating component 36 places.Adopt this form of the composition, sensitivity prescan operating component 36 constitutes generation can implement sequence signal under the condition that videotapes of sensitivity prescan and all operations simultaneously, and is sent to sequence signal controller Control Component 38 places.
Magnatic Resonance Imaging (MRI) apparatus 20B can implement all operations when implementing the operation of sensitivity prescan.At this moment videotape sequence signal, for example in FFE, TE can be set at two echoes of 4.5 milliseconds of (ms)/9.0 millisecond (ms), the angle of twist is set at about 5～10 degree.And, can find the solution Distribution of Magnetic Field and carry out all operations according to the signal phase difference between two echoes, the data of 4.6 milliseconds (ms) are inferred as sensitivity use data.
Therefore, if adopt Magnatic Resonance Imaging (MRI) apparatus 20B, except can obtaining technique effect that Magnatic Resonance Imaging (MRI) apparatus 20A had, can also implement videotape operation by higher efficient.
And in Magnatic Resonance Imaging (MRI) apparatus 20A, 20B, be not phased matrix coils 24b, can also be with head with different various coils of purpose such as coils, various array coil, surface coils, the signal receiving coil when implementing main scanning is promptly as the main coil of RF coil 24.And RF coil 24 or main coil also can adopt single coil to constitute.
If adopt this form of the composition, also can use WB coil 24a self to produce the sensitivity map diagram data of WB coil 24a.Phased matrix coils 24b is little for the sensitivity fluctuation ratio of WB coil 24a, even but further make equipment miniaturization from now on, also can't rise and fall basically and ignore the sensitivity that WB coil 24a produces.So,, then can easily make the further miniaturization of device if, make the sensitivity map diagram data of WB coil 24a only with the signal receiving coil of WB coil 24a when implementing the sensitivity prescan.
On the other hand, if the pictorial data that will be obtained by the signal receiving coil in the time of only will implementing main scanning is as initial data, generate sensitivity map diagram data, then also can adopt other coil outside the signal receiving coil when implementing main scanning, the signal receiving coil during as enforcement sensitivity prescan.
And, can also implement combination mutually to Magnatic Resonance Imaging (MRI) apparatus 20,20A, the 20B of above-mentioned form of implementation, or omit wherein a part of element and function.
Claims (4)
1. MR imaging apparatus is characterized in that comprising:
Assembly is implemented in scanning, implements to be used to generate the scanning operation of the sensitivity map diagram data of RF coil;
The zone suppresses processing components, to the pictorial data that obtains by aforementioned scanning operation be positioned near the position no signal zone have the signal area to implement the zone to suppress to handle;
Sensitivity map diagram data formation component uses the earlier figures image data of implementing after the zone suppresses to handle, and generates sensitivity map diagram data;
The smoothing processing assembly is implemented three-dimensional The disposal of gentle filter to aforementioned sensitivity map diagram data.
2. Magnatic Resonance Imaging (MRI) apparatus as claimed in claim 1 is characterized in that also comprising:
The zone that zone increase processing is implemented in the detected external no signal zone of being positioned at of aforementioned sensitivity map diagram data increases processing components.
3. Magnatic Resonance Imaging (MRI) apparatus as claimed in claim 1 is characterized in that also comprising:
By being weighted, come aforementioned sensitivity map diagram data is implemented the bedding angle weighting processing components of correction along the cutting bedding angle.
4. the data processing method of a Magnatic Resonance Imaging (MRI) apparatus is characterized in that comprising:
The signal area that has that is positioned near the position no signal zone of the pictorial data that the scanning of the sensitivity map diagram data of implementing to be used to generate the RF coil is obtained is implemented the zone and is suppressed the step handled;
Use the earlier figures image data of implementing after the zone suppresses to handle, generate the step of sensitivity map diagram data;
Aforementioned sensitivity map diagram data is implemented the step of three-dimensional The disposal of gentle filter.
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| US10191126B2 (en) * | 2013-04-04 | 2019-01-29 | Regents Of The University Of Minnesota | Systems and methods for spatial gradient-based electrical property properties tomography using magnetic resonance imaging |
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| JPH09238920A (en) * | 1996-03-12 | 1997-09-16 | Toshiba Corp | Magnetic resonance imaging apparatus |
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| EP2210556B1 (en) | 2019-04-10 |
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